1. Field of the Invention
The present invention relates in general to an instrument for ejecting material, and more particularly to an instrument useful in ejecting dental impression material for making dental impressions.
2. Brief Description of Prior Art
For a preparation of a dental prosthesis, an impression of the teeth and the part of the jaw adjacent to these teeth must be provided to the dental technician. Prior to this time, a dentist has usually completed preparation of the patient for taking the impression, which involves both cleaning the area and adequately exposing the tooth at or below the gum line, as necessary, for reception of the impression material. The groove defined between the tooth and gum in this region is usually referred to as the “sulcus”. It is important that each concave and convex surface on which the impression material is to be placed be dry, because the impression material will not otherwise adhere. The presence of seepage and the physical characteristics of the impression material tend to introduce voids, bubbles and incompletely filled areas into the impression.
Different techniques have previously been employed for allowing the impression material to be properly applied.
To obtain clear access to the sulcus and the margin line which the casting base is to follow, a packing material or gingival retraction cord is often used to separate the gum from the tooth in this region. However, this technique is time-consuming and often involves traumatizing of the gingival tissues, frequently causing bleeding. Such bleeding complicates the impression taken, often requiring the dentist to discontinue further work until the bleeding has stopped. Further, seepage usually begins as soon as the packing material is taken out, or can be continuous if no packing is used. As stated, impression material will not adhere to wet surface but instead, slips to another region.
The prior art techniques known are very time-consuming causing frustration to the dentist, and often involve traumatizing of the gingival tissues, frequently causing bleeding.
It should be kept in mind that an accurate impression must be taken as expeditiously as possible, for the benefit of both the patient and the dentist. To accomplish this a versatile instrument capable of being used in different ways to overcome different problems is highly desirable but is not heretofore been available.
An object of the present invention is to provide an applicator particularly useful in making dental impressions which reduces or avoids the above drawbacks.